• Journal of Intelligence and Information Systems
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• v.17 no.4
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• pp.255-277
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• 2011

Product Service System(PSS), which is an integrated combination of product and service, provides new value to customer and makes companies sustainable as well. The objective of this paper draws Critical Successful Factors(CSF) of PSS through multiple case study. First, we review various concepts and types in PSS and Platform business literature currently available on this topic. Second, after investigating various cases with the characteristics of PSS and platform business, we select four cases of 'iPod of Apple', 'Kindle of Amazon', 'Zune of Microsoft', and 'e-book reader of Sony'. Then, the four cases are categorized as successful and failed cases according to criteria of case selection and PSS classification. We consider two methodologies for the case selection, i.e., 'Strategies for the Selection of Samples and Cases' proposed by Bent(2006) and the seven case selection procedures proposed by Jason and John(2008). For case selection, 'Stratified sample and Paradigmatic cases' is adopted as one of several options for sampling. Then, we use the seven case selection procedures such as 'typical', 'diverse', 'extreme', 'deviant', 'influential', 'most-similar', and 'mostdifferent' and among them only three procedures of 'diverse', 'most?similar', and 'most-different' are applied for the case selection. For PSS classification, the eight PSS types, suggested by Tukker(2004), of 'product related', 'advice and consulancy', 'product lease', 'product renting/sharing', 'product pooling', 'activity management', 'pay per service unit', 'functional result' are utilized. We categorize the four selected cases as a product oriented group because the cases not only sell a product, but also offer service needed during the use phase of the product. Then, we analyze the four cases by using cross-case pattern that Eisenhardt(1991) suggested. Eisenhardt(1991) argued that three processes are required for avoiding reaching premature or even false conclusion. The fist step includes selecting categories of dimensions and finding within-group similarities coupled with intergroup difference. In the second process, pairs of cases are selected and listed. The second step forces researchers to find the subtle similarities and differences between cases. The third process is to divide the data by data source. The result of cross-case pattern indicates that the similarities of iPod and Kindle as successful cases are convenient user interface, successful plarform strategy, and rich contents. The differences between the successful cases are that, wheares iPod has been recognized as the culture code, Kindle has implemented a low price as its main strategy. Meanwhile, the similarities of Zune and PRS series as failed cases are lack of sufficient applications and contents. The differences between the failed cases are that, wheares Zune adopted an undifferentiated strategy, PRS series conducted high-price strategy. From the analysis of the cases, we generate three hypotheses. The first hypothesis assumes that a successful PSS system requires convenient user interface. The second hypothesis assumes that a successful PSS system requires a reciprocal(win/win) business model. The third hypothesis assumes that a successful PSS system requires sufficient quantities of applications and contents. To verify the hypotheses, we uses the cross-matching (or pattern matching) methodology. The methodology matches three key words (user interface, reciprocal business model, contents) of the hypotheses to the previous papers related to PSS, digital contents, and Information System (IS). Finally, this paper suggests the three implications from analyzed results. A successful PSS system needs to provide differentiated value for customers such as convenient user interface, e.g., the simple design of iTunes (iPod) and the provision of connection to Kindle Store without any charge. A successful PSS system also requires a mutually benefitable business model as Apple and Amazon implement a policy that provides a reasonable proft sharing for third party. A successful PSS system requires sufficient quantities of applications and contents.

• Korean Journal of Weed Science
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• v.16 no.2
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• pp.114-121
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• 1996

This study was conducted to investigate seed germination, seedling growth, and responses to herbicides of Bidens tripartita L. When the field-collected seeds were stored under a dry-room temperature, dry-low temperature, wet-low temperature, or dry-high temperature condition, no seeds were germinated in a growth chamber with 14 hr photoperiod up to 35 days after the storage. Exceptionally, however, some seeds stored under a wet-room temperature condition were germinated after 25 days of the storage. This might be due to the fact that the seed coats were damaged by fungi which developed during the storage. Seeds stored under a wet-low temperature condition (stratification) began to be germinated after 3 months of the storage and the germination rate increased with a prolonged stratification. Almost all seeds were germinated after 9 months of the stratification. These results suggest that the dormancy of B. tripartita L. seeds relate to the seed coat and thus several attempts were made to induce seed germination through damaging or weakening the seed coat. Freezing($-20^{\circ}C$), drying($100^{\circ}C$), or swelling($40^{\circ}C$) of the seeds was not effective to induce the germination. Treatments of concentrated sulfuric acid, $KNO_3$, or gibberellin to the seeds had no effect on inducing the germination. However, ethrel had a stimulatory effect on the germination of the seeds with an optimum concentration of 250ppm. A seed cutting was also effective to induce the germination, but seedlings from the seeds had cutted cotyledons. Germination of the stratified seeds varied with the temperature condition to which they were subjected, but not with light. The germination rate was the highest at 35 - $40^{\circ}C$. Although the seeds were not able to germinate under a submerged condition, seedlings after 2-leaf-stage exhibited better growth under a submerged or a subirrigated condition than under an upland condition. Among the herbicides tested, pyrazosulfuton-ethyl, linuron, and bentazone were found to be effective for controlling B. tripartita L., having more herbicidal effect with an earlier application.

• Journal of the Korean Academy of Child and Adolescent Psychiatry
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• v.11 no.1
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• pp.79-90
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• 2000

Objective：This study was performed in order to develop a measuring instrument for assessing and predicting delinquent behavior of the adolescents in Korea. Methods：This study was methodological research for developing a questionnaire for measuring delinquent behavior. Through the relevant literature review and personal interview using open-ended question with 12 adolescents in schools, outpatient basis and the juvenile corrective institutions, the author developed a pre-questionnaire with 31 items for assessing delinquent behavior among delinquentprone adolescents. Statistical method employed were test-retest reliability and Cronbach's alpha coefficient for testing reliability and factor analysis for testing validity of this questionnaire, and t-test for mean difference between student adolescents and delinquent adolescents, using SAS program. Subject served for this study consisted of 2,177 adolescents including 1,206 students and 971 delinquent adolescents by proportional stratified random sampling method. Results：1) Three stable factors were emerged and these contributed 52.2% of the variance in the total score. All 31 items loaded above .40 on each factor. 2) Factor I was named as antisocial delinquent behavior(17 items), factor II was named as aggressive delinquent behavior(8 items), and factor III was named as psychopathic delinquent behavior(6 items). 3) Comparison of these 3 factors between student adolescents and delinquent adolescents showed that there was a significant difference in factor Ⅰ(t=-42.91(student), -41.71(delinquent), p=.0001), factor II(t=-34.10(student), -35.72(delinquent), p=.0001), factor III(t=-14.24(student), -14.26 (delinquent), p=.0000), and total score(t=37.02(student), -36.38(delinquent), p=.0001). 4) Internal consistency reliability was tested by Cronbach's ${\alpha}$. Cronbach's ${\alpha}$ was .952 for total 31 items and .950, .866 and .721 for each 3 factors related to delinquent behavior. Conclusions：The author confirmed that this scale can use for measuring delinquent behavior, and hope to make a contribution to screening test and prevention of juvenile delinquency in Korea.

• Journal of the Korean Academy of Child and Adolescent Psychiatry
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• v.8 no.1
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• pp.57-69
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• 1997

Objective：At the present time in Korea, for a considerable proportion of children and adolescent, delinquent behavior and violence has become as a way of life in their lives and a major social problem issue as well. The contributing factors to this problem were assumed to be the negative interaction between family environment and character of adolescent. The purpose of this study is to search the relationship between these constructs and juvenile delinquency. Method：Data were collected through questionnaire survey over a period of 2 months. Subjects served for this study consisted of 1,863 adolescents including 657 delinquent adolescents and 1,206 student adolescents in Korea, sampled from Korean student population and delinquent adolescent population confined in juvenile corrective institutions, using proportional stratified random sampling method. Their age ranged between 12 and 18 years. Data were analysed by IBM PC using SAS program. Statistical methods employed were Chi-square and principal component analysis. Results：The results of this study were as follows：Inconsistency by parental child rearing patterns tended to affect delinquent behavior among delinquent adolescents. On the other hand, adolescent students were consistently reared by their parent with democratic, flexible, trusting their children and reward-oriented attitudes. In comparison of both parents in the degree of influence on their children, it was revealed that paternal child rearing pattern was more influential on their children’s behaviors than maternal’s. The psychological instability of family, disharmonious parent-child relationships tended to be contributing to delinquent behavior among delinquent adolescents. Especially, It was an interesting finding that student’s mother is the higher employed than delinquent’s mother. However working mother was more prevalent in the student’ adolescents than in student adolescents in previous studies. The delinquent adolescents have more depressive trend, more complaints of psychosomatic symptoms, the higher degree of need frustration, the more maladaptive and antisocial personality pattern than student adolescents. Conclusion：Recently, many studies on association between family factor, character of adolescent and juvenile delinquent behavior have produced relatively consistent results. This study showed that family environment and character trait of adolescent also were linked with delinquent behavior such as smoking, drinking, runaway and physical assaults etc. The results of this survey may provide impetus for future speculation and study of correlation or reciprocal interaction between family factor, character trait of adolescent and delinquent behavior during adolescence and beyond.

• Journal of dental hygiene science
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• v.16 no.3
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• pp.217-224
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• 2016

The aim of this study was to evaluate whether the number of existing permanent teeth is associated with chronic obstructive pulmonary disease (COPD) in a representative sample of Korean adults. Data from 3,107 subjects who participated in the 2009 Korea National Health and Nutrition Examination Survey were examined. The dependent variable was COPD and the independent variable was the number of existing permanent teeth. Spirometry results were classified into three groups (normal pattern, restrictive pattern, and obstructive pattern) by trained technicians. We used dichotomized COPD variables (no vs. yes). The number of existing permanent teeth was evaluated by oral examination and divided into 3 groups (0~19, 20~27, and 28). Demographic factors (age group and sex group), socioeconomic status (education and income), health behaviors (smoking and drinking), oral health and behavior (frequency of toothbrushing; periodontitis; decayed, missing, filled, permanent teeth index; and denture status), and general health status (body mass index, diabetes mellitus, and hypertension) were included as confounders in the analysis. Bivariate analysis and multivariate logistic regression analyses including confounders were applied, and all analyses considered a complex sampling design. Stratified analysis was performed by smoking status. After controlling for various confounders, there was a significant association between the number of existing permanent teeth and COPD (odds ratio [OR], 1.90; 95% confidence interval [CI], 1.20~3.00 for the 20~27 group; OR, 3.93; 95% CI, 1.75~8.84 for the 0~19 group). The association was more significant in current smokers (OR, 8.90; 95% CI, 2.53~31.33). Our data indicate that the number of existing permanent teeth was independently associated with COPD, especially in current smokers. Further longitudinal research is needed to determine whether oral health promotion plays a role in the improvement of lung function and prevention of COPD.

• Journal of Gastric Cancer
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• v.9 no.4
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• pp.246-255
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• 2009

Purpose: The objectives of this study were to investigate the impact of the number of resected lymph nodes on the survival of gastric cancer patients who underwent curative resection, and to evaluate the cut-off values that can have an influence on survival on the tumor stage-stratified analysis. Materials and Methods: The subjects were 949 gastric cancer patients who underwent curative resection at Korea University Medical Center from 1992 to 2002. They were classified according to the depth of tumor invasion, and the influence of the number of resected lymph nodes on survival was investigated. The cut-off value for the number of resected lymph nodes was determined as the smallest value that showed a significant survival difference. Results: The tumor size, location, lymph node stage, the number of metastatic lymph nodes and the number of resected lymph nodes were significantly different according to the tumor stage. The average number of resected lymph nodes was about 39, and it showed linear correlation with the number of metastatic lymph nodes. On the Cox proportional hazard model, the cut-off values of the number of resected lymph nodes, as corrected by the number of metastatic lymph nodes, was 14 for all the patients, 15 for the pT1 patients, 28 for the pT2 patients and 37 for the pT3 patients, respectively. Conclusion: Retrieving a number of lymph nodes that is more than the cut-off value could improve the survival of gastric cancer patients. Surgeons should also make efforts to perform an exact and thorough D2 lymph node dissection. Therefore, we urge surgeons to perform D2 dissection and pathologists should examine an certain exact number of lymph nodes.

• Genomics & Informatics
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• v.16 no.2
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• pp.36-41
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• 2018

Kawasaki disease (KD) is an acute febrile vasculitis predominately affecting infants and children. The dominant incidence age of KD is from 6 months to 5 years of age, and the incidence is unusual in those younger than 6 months and older than 5 years of age. We tried to identify genetic variants specifically associated with KD in patients younger than 6 months or older than 5 years of age. We performed an age-stratified genome-wide association study using the Illumina HumanOmni1-Quad BeadChip data (296 cases vs. 1,000 controls) and a replication study (1,360 cases vs. 3,553 controls) in the Korean population. Among 26 candidate single nucleotide polymorphisms (SNPs) tested in replication study, only a rare nonsynonymous SNP (rs4365796: c.1106C>T, p.Thr369Met) in the lymphoid enhancer binding factor 1 (LEF1) gene was very significantly associated with KD in patients younger than 6 months of age (odds ratio [OR], 3.07; $p_{combined}=1.10{\times}10^{-5}$), whereas no association of the same SNP was observed in any other age group of KD patients. The same SNP (rs4365796) in the LEF1 gene showed the same direction of risk effect in Japanese KD patients younger than 6 months of age, although the effect was not statistically significant (OR, 1.42; p = 0.397). This result indicates that the LEF1 gene may play an important role as a susceptibility gene specifically affecting KD patients younger than 6 months of age.

• Journal of The Korean Association For Science Education
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• v.19 no.2
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• pp.185-193
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• 1999

The long term trend of studensts' science achievement is a very important factor to check the effectiveness of science educational policy. However, up to date no such effort to understand the trend of Korean students' science achievement has been put into action. Recently, the Science Education Center in Korea National University of Education has been attempted to collect nation wide data for students' science achievement. The first part of the effort was to develop item pools. This study was the second part to collect nation wide data and to check any change during the two year time interval. In this study, the item pools developed by Kwon et. al.(1998) were used with some modification. The data were collected two times; February 1997 and March 1999. The subjects collected nationally were 8,766 students in 1997 and were 4,398 in 1999. The subjects were collected randomly but stratified by region and sex. As the results, the trends of achievement change during the two years were different from elementary to high school. The achievement scores were decreased in elementary schools and increased in high school. In case of middle schools, the change was not significant. However, even in elementary schools the knowledge on theory was increased significantly while knowledge on facts and principles were decreased. In contrast, the knowledge on fact showed the most increase in high schools. In this study, the data were analysed in light of region, sex, behavioral objective levels(ability) and context of test items. The science achievement monitoring system developed by the Science Education Center in Korea National University of Education can be an effective tool for monitoring students' achievement on the national level.

• Tuberculosis and Respiratory Diseases
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• v.42 no.2
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• pp.149-155
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• 1995

Background: Cytokeratin 19 is 40KD acidic molecule whose distribution is restricted to simple or pseudo-stratified epithelia, such as the epithelial layer of the bronchial tree. Immunohistochemical study have shown that cytokeratin 19 is overexpressed in lung carcinoma tissue. An immunoradiometric assay, CYFRA 21-1 has been developed using two monoclonal antibody, BM 19-21 and KS 19-1, reactive to different epitopes on cytokeratin 19. We studied the diagnostic value of CYFRA 21-1 in lung cancer. Method: The serum CYFRA 21-1 level using immunoradiometric kit(ELSA-CYFRA 21-1) was measured in 54 patients who admit to Yeungnam University Hospital from April, 1993 to August, 1994. Lung cancer group was 39 primary lung cancer patients(19 patients with squamous cell carcinoma, 11 patients with adenocarcinoma and 9 patients with small cell carcinoma). Control group was 15 patients with non malignant lung diseases(8 patients with pulmonary tuberculosis, 3 patients with chronic obstructive pulmonary disease, 2 patients with pneumonia and 2 patients with chronic obstructive pulmonary disease combined with pulmonary tuberculosis). Results: The mean serum value of CYFRA 21-1 was $20.2{\pm}4.7ng/ml$ in squamous cell carcinoma, $7.2{\pm}1.6ng/ml$ in adenocarcinoma and $15.5{\pm}4.7ng/ml$ in non-small cell lung cancer. The serum value of CYFRA 21-1 in control group was $1.7{\pm}0.5ng/ml$. All of the serum values of 3 histologic types were significantly higher than that of control group(p<0.01). The serum value of CYFRA 21-1 of squamous cell carcinoma was significantly higher than that of adenocarcinoma(p <0.05). Serum value of CYFRA 21-1 in small cell lung cancer was $2.9{\pm}0.9ng/ml$ and not significantly different compared with control group. Using cut off value of 3.3ng/ml, sensitivity and specificity was 11.1%, 65.2% in small cell lung cancer, 70.0%, 62.5% in non-small cell lung cancer, 73.7%, 75% in squamous cell carcinoma and 63.6%, 78.9% in adenocarcinoma, respectively. Conclusion: The serum levels of CYFRA 21-1 may be useful in diagnosis of non-small cell lung carcinoma, especially in squamous cell carcinoma with its high specificity.

• Tuberculosis and Respiratory Diseases
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• v.58 no.5
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• pp.490-497
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• 2005

Background : The paraoxonase enzyme plays a significant role in the detoxification of various organophosphorous compounds in mammals, and paraoxonase (PON) 1 is one of the endogenous free-radical scavenging systems in the human body. In this study, we investigated the interaction between cigarette smoking and the genetic polymorphism of PON1 with lung cancer in Korean males. Methods : Three hundred thirty five patients with lung cancer and an equal number of age-matched controls were enrolled in this study. Every subject was asked to complete a questionnaire concerning their smoking habits and alcohol drinking habits. A 5' exonuclease assay (TaqMan) was used to genotype the PON1 Q192R polymorphism. The effects of smoking habits and drinking habits, the PON1 Q192R polymorphism and their interactions were statistically analyzed. Results : Cigarette smoking and the Q/Q genotype of PON1 were significant risk factors for lung cancer. Individuals carrying the Q/Q genotype of PON1 were at a higher risk for lung cancer as compared with those individuals carrying the Q/R or R/R genotype (odds ratio, 2.84; 95% confidence interval, 1.69 - 4.79). When the groups were further stratified by the smoking status, the Q/Q PON1 was associated with lung cancer among the current or ex-smokers (odds ratio, 2.56; 95% confidence interval, 1.52 - 4.31). Current smokers or ex-smokers who had the Q/Q genotype showed an elevated risk for lung cancer (odds ratio: 15.50, 95% confidence interval: 6.76 - 35.54) as compared with the group of subjects who never smoked, and had the Q/R or R/R genotype. The odds ratios (95% confidence interval) of smokers with the PON1 Q/Q type compared to the nonsmokers with the PON1 Q/R or R/R type were 53.77 (6.55 - 441.14) for squamous cell carcinoma, 6.25 (1.38 - 28.32) for adenocarcinoma, and 59.94 (4.66 - 770.39) for small cell carcinoma, and these results were statistically significant. Conclusion : These results suggest that cigarette smoking and the PON1 Q/Q genotype are risk factors for lung cancer. The combination of cigarette smoking and the PON1 Q/Q genotype significantly increased the lung cancer risk irrespective of the histologic type of cancer.